/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011  Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/

#include "hsTypes.h"

#include "plShadowSlave.h"
#include "plTweak.h"

#include <float.h>

static const hsScalar kMinMinZ = 1.f; // totally random arbitrary number (has to be > 0).

bool plShadowSlave::ISetupOrthoViewTransform()
{
	hsBounds3Ext bnd = fCasterWorldBounds;

	bnd.Transform(&fWorldToLight);

	hsScalar minZ = bnd.GetMins().fZ;
	hsScalar maxZ = bnd.GetCenter().fZ + fAttenDist;

	hsScalar minX = bnd.GetMins().fX;
	hsScalar maxX = bnd.GetMaxs().fX;

	hsScalar minY = bnd.GetMins().fY;
	hsScalar maxY = bnd.GetMaxs().fY;


	hsMatrix44 proj;
	proj.Reset();
	proj.NotIdentity();

	// First the LightToTexture, which uses the above pretty much as is.
	// Note the remapping to range [0.5..width-0.5] etc. 
	// About this kAdjustBias. According to the docs, it should be 0.5,
	// and on the perspective projection 0.5 works great. But on the
	// directional (ortho) projection, it just makes the mapping wrong,
	// and an offset of zero works great. This could be a driver bug, or
	// hardware "dependency" (read IHV bug), but whatever, zero is working
	// now. Might need to adjust for new drivers or other hardware.
	const hsScalar kAdjustBias = 0.0f;
	proj.fMap[0][0] = 1.f / (maxX - minX);
	proj.fMap[0][3] = -minX / (maxX - minX) + kAdjustBias / fWidth;
	proj.fMap[1][1] = -1.f / (maxY - minY);
	proj.fMap[1][3] = -minY / (maxY - minY) + kAdjustBias / fHeight;
	proj.fMap[2][2] = 1.f;
	proj.fMap[3][3] = 1.f;

	fWorldToTexture = proj * fWorldToLight;

	// Now the LightToNDC. This one's a little trickier, because we want to compensate for
	// having brought in the viewport to keep our border constant, so we can clamp the 
	// projected texture and not have the edges smear off to infinity.
	// Like the adjust bias above, this part is correct in theory, but only
	// screws things up (increases Z-acne).
#if 0
	hsScalar delX = maxX - minX;
	minX += delX / (fWidth * 0.5f);
	maxX -= delX / (fWidth * 0.5f);
	hsScalar delY = maxY - minY;
	minY += delY / (fHeight * 0.5f);
	maxY -= delY / (fHeight * 0.5f);
#endif 


	fView.SetView(hsPoint3(minX, minY, minZ), hsPoint3(maxX, maxY, maxZ));
	fView.SetScreenSize((UInt16)fWidth, (UInt16)fHeight);
	fView.SetCameraTransform(fWorldToLight, fLightToWorld);
	fView.SetPerspective(false);
	fView.SetViewPort(0, 0, hsScalar(fWidth), hsScalar(fHeight), false);

	fLightDir = fLightToWorld.GetAxis(hsMatrix44::kUp);
	SetFlag(kPositional, false);
	SetFlag(kReverseCull, true);
	
	return true;
}

bool plShadowSlave::ISetupPerspViewTransform()
{
	hsBounds3Ext bnd = fCasterWorldBounds;

	bnd.Transform(&fWorldToLight);

	hsScalar minZ = bnd.GetMins().fZ;
	hsScalar maxZ = bnd.GetCenter().fZ + fAttenDist;

	if( minZ < kMinMinZ )
		minZ = kMinMinZ;

	// EAP
	// This is my hack to get the Nexus age working.  The real problem
	// is probably data-side.  I take full responsibility for this
	// hack-around breaking the entire system, loosing data, causing
	// unauthorized credit card transactions, etc.		
	if (_isnan(bnd.GetMins().fX) || _isnan(bnd.GetMins().fY))
		return false;
	if (_isnan(bnd.GetMaxs().fX) || _isnan(bnd.GetMaxs().fY))
		return false;

	hsScalar cotX, cotY;
	if( -bnd.GetMins().fX > bnd.GetMaxs().fX )
	{
		hsAssert(bnd.GetMins().fX < 0, "Empty shadow caster bounds?");
		cotX = -minZ / bnd.GetMins().fX;
	}
	else
	{
		hsAssert(bnd.GetMaxs().fX > 0, "Empty shadow caster bounds?");
		cotX = minZ / bnd.GetMaxs().fX;
	}

	if( -bnd.GetMins().fY > bnd.GetMaxs().fY )
	{
		hsAssert(bnd.GetMins().fY < 0, "Empty shadow caster bounds?");
		cotY = -minZ / bnd.GetMins().fY;
	}
	else
	{
		hsAssert(bnd.GetMaxs().fY > 0, "Empty shadow caster bounds?");
		cotY = minZ / bnd.GetMaxs().fY;
	}

	hsMatrix44 proj;
	proj.Reset();
	proj.NotIdentity();

	// First the LightToTexture, which uses the above pretty much as is.
	// Note the remapping to range [0.5..width-0.5] etc. Also, the perspective
	// divide is by the 3rd output (not the fourth), so we make the 3rd
	// output be W (instead of Z).
	// This also means that our translate goes into [i][2] instead of [i][3].
#if 0
	proj.fMap[0][0] = cotX * 0.5f;
	proj.fMap[0][2] = -0.5f * (1.f + 0.5f/fWidth);
	proj.fMap[1][1] = cotY * 0.5f;
	proj.fMap[1][2] = -0.5f * (1.f + 0.5f/fHeight);
#else
	plConst(hsScalar) kBiasScale(1.f);
	plConst(hsScalar) kBiasTrans(1.f);
	proj.fMap[0][0] = cotX * 0.5f * ( hsScalar(fWidth-2.f) / hsScalar(fWidth) ) * kBiasScale;
	proj.fMap[0][2] = 0.5f * (1.f - kBiasTrans * 0.5f/fWidth);
	proj.fMap[1][1] = -cotY * 0.5f * ( hsScalar(fHeight-2.f) / hsScalar(fHeight) ) * kBiasScale;
	proj.fMap[1][2] = 0.5f * (1.f - kBiasTrans * 0.5f/fHeight);
#endif

#if 0 // This computes correct Z, but we really just want W in 3rd component. HACKFISH
	proj.fMap[2][2] = maxZ / (maxZ - minZ);
	proj.fMap[2][3] = -minZ * maxZ / (maxZ - minZ);
#elif 1
	proj.fMap[2][2] = 1.f;
	proj.fMap[2][3] = 0;
#endif
	proj.fMap[3][2] = 1.f;
	proj.fMap[3][3] = 0;

	fWorldToTexture = proj * fWorldToLight;

	// Now the LightToNDC. This one's a little trickier, because we want to compensate for
	// having brought in the viewport to keep our border constant, so we can clamp the 
	// projected texture and not have the edges smear off to infinity.
	cotX -= cotX / (fWidth * 0.5f);
	cotY -= cotY / (fHeight * 0.5f);

	hsScalar tanX = 1.f / cotX;
	hsScalar tanY = 1.f / cotY;
	fView.SetView(hsPoint3(-tanX, -tanY, minZ), hsPoint3(tanX, tanY, maxZ));
	fView.SetScreenSize((UInt16)fWidth, (UInt16)fHeight);
	fView.SetCameraTransform(fWorldToLight, fLightToWorld);
	fView.SetPerspective(true);
	fView.SetViewPort(0, 0, hsScalar(fWidth), hsScalar(fHeight), false);

	fLightPos = fLightToWorld.GetTranslate();
	SetFlag(kPositional, true);

	return true;
}